As an efficient and environment-friendly energy, natural gas has become an inevitable choice for improving environment, achieving the low carbon economy and the sustainable development all around world. However, flow resistance produced in the course of the gas pipeline transportation caused large loss of transportation energy and brought down the transportation capacity. Therefore, this paper have developed a deep researches on the interaction mechanism between a drag reduction agent (DRA) and the inner surface of natural gas pipeline, the flow pattern improvement regularity about DRA membrane acting on the near-wall region of the pipeline, the relation between the flow pattern improvement and friction resistance, the effect regularity of DRA on the friction coefficient of the pipeline inner surface, and the relation between the alternation of the friction coefficient and the drag reduction. According to all above studies, the fundamental reason for flow resistance of the gas transportation has been found, and the drag reduction mechanism of the gas pipeline transportation has also been hold of. Field test shows that the application of the DRA in the course of the gas pipeline transportation reduced the friction loss by 12%-16.5%, and raised the transfer efficiency by 8%-12%.